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41b21af388
Prior to commit9fe55eea7e("Fix race when checking i_size on direct i/o read"), an unaligned direct read past end of file would trigger EOF, since generic_file_aio_read detected this read-at-EOF condition and skipped the direct IO read entirely, returning 0. After that change, the read now reaches dio_generic, which detects the misalignment and returns EINVAL. This consolidates the generic direct-io to follow the same behavior of filesystems. Apparently, this fix will only affect ocfs2 since other filesystems do this verification before calling do_blockdev_direct_IO, with the exception of f2fs, which has the same bug, but is fixed in the next patch. it can be verified by a read loop on a file that does a partial read before EOF (On file that doesn't end at an aligned address). The following code fails on an unaligned file on filesystems without prior validation without this patch, but not on btrfs, ext4, and xfs. while (done < total) { ssize_t delta = pread(fd, buf + done, total - done, off + done); if (!delta) break; ... } Fix this regression by moving the misalignment check to after the EOF check added by commit74cedf9b6c("direct-io: Fix negative return from dio read beyond eof"). Based on a patch by Jamie Liu. Link: https://lore.kernel.org/r/20201008062620.2928326-4-krisman@collabora.com Reported-by: Jamie Liu <jamieliu@google.com> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com> Signed-off-by: Jan Kara <jack@suse.cz>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.